1. Field of the Invention
The present invention relates to a drive transmission device that transmits driving power of a driving motor through a motor pinion gear and a gear train including a reduction gear and other gears; and to an image forming apparatus including the drive transmission device.
2. Description of the Related Art
In one example, an image forming apparatus, such as a copying machine or a printer that forms an image onto a sheet by an electrophotography method, is provided with a drive transmission device that transmits driving power of a driving motor to various rollers through a gear train, thereby rotationally driving each roller.
Japanese Unexamined Patent Application Publication No. 2006-275071 (Patent Document 1), disclosing a drive transmission device, proposes a structure in which, in order to increase gear strength and restrict abnormal noise generated when gears contact each other, silicone oil (serving as a lubricant) and amorphous silica (serving as a filler) are added to polyacetal resin (serving as a base material of the gears).
A clearance exists between the inside diameters of gear bosses of the drive transmission device and the rotation sliding bosses that support the gears. Therefore, the orientations of the gears are not stable and adversely affect engagement of the gears. As a result, abnormal noise or vibration is generated.
In related drive transmission devices, the rotation sliding bosses that rotatably support the gears of a gear train are each mounted one-by-one by caulk to a metallic motor mounting plate. As a result, the number of components is increased, and mounting operations require a large number of man-hours and increase costs.
To overcome these problems, the rotation sliding bosses may be integrally formed at a resin housing side. However, when an attempt is made to realize such a structure, a reduction gear and an output shaft (pinion gear) of a motor cannot be positioned with high precision with respect to each other. In addition, the engagement of the gears is adversely affected, thereby generating vibration or abnormal noise as mentioned above.
Accordingly, a first object of the present invention is to provide a drive transmission device that can prevent abnormal noise or vibration from being generated by stabilizing the orientation of the gears, and to provide an image forming apparatus including the drive transmission device.
A second object of the present invention is to provide a drive transmission device that can reduce costs, reduce the number of man-hours, and reduce the number of components by providing rotation sliding bosses, which rotatably support gears, formed integrally with and so as to protrude from a resin member differing from a motor mounting plate; and to provide an image forming apparatus including the drive transmission device.